Environmental simulation chamber and related operation method

Abstract

An environment simulation chamber (100) comprising: a refrigeration device equipped with a refrigeration device (10) having a closed circuit (C) in which a refrigerant fluid circulates, said closed circuit (C) being equipped with at least one compressor (2); a cooling device (3) for the refrigerant fluid; the invention relates to a simulation chamber (100) comprising a refrigerant fluid, expansion means (4) and evaporation means (5) for said refrigerant fluid, said chamber (100) further comprising an adiabatic space (20) into which a sample (21) to be tested is inserted, and wherein said evaporation means (5) is adapted to adjust the internal temperature of said adiabatic space (20), characterized in that said refrigerant fluid is carbon dioxide.

Description

Technical Field

[0001] The invention relates to an environmental simulation chamber and a related operating method. Background Art

[0002] It is known that there is an environmental simulation chamber comprising a refrigeration device, the refrigeration device is equipped with a refrigeration device, the refrigeration device has a closed circuit, and a refrigerant fluid circulates in the closed circuit. The closed circuit is equipped with at least one compressor, a cooling device for the refrigerant fluid, an expansion device for the refrigerant fluid and an evaporation device. The chamber further comprises an insulating space, in which the sample to be tested is inserted, and the evaporation device cooperates with the expansion device therein to be suitable for regulating the temperature inside the insulating space to test the behavior of the sample under various environmental conditions, even extreme conditions. Still according to the prior art, the refrigerant fluid is generally known as R449.

[0003] However, this refrigerant fluid also has disadvantages.

[0004] In fact, although the refrigeration equipment using this gas allows very precise and fast temperature control in the insulated space of the environmental simulation chamber, the GWP of R449 gas is quite high. It should be noted that the refrigerant should have a relatively low CO2 equivalent. In fact, its relative global warming potential or GWP should be as low as possible to avoid damage to the environment in the event of a refrigerant leak. GWP measures the limited mass of greenhouse gases that cause global warming. This value is determined by considering carbon dioxide as a reference and is therefore a reference value. Therefore, GWP describes the average warming impact of a given gas or gas mixture over a certain time interval, in this article for 100 years. Regarding the definition of CO2 equivalent or its respective GWP, reference will be made to Regulation (EU) No. 517 / 2014 of the European Parliament and the Council (EU) herein and hereinafter.

[0005] Therefore, the higher the GWP value associated with a gas, the greater the risk to the environment if that gas is released into the atmosphere.

[0006] Known environmental simulation chambers operate using gases with very low GWP.

[0007] For example, patent WO2021 / 124135 under the name of ATT describes an environmental simulation chamber that uses a gas mixture with an extremely low GWP value, even below 380 within 100 years.

[0008] In any case, the trend is to find a gas for climate-controlled chambers whose GWP value is even lower than the already extremely low GWP value of the refrigerant mixture described in document WO2021 / 124135 in the name of the applicant.

[0009] Document US2019 / 093926 under the name of Haack Christian describes an air-conditioned test chamber comprising a test space for receiving test materials and which can be isolated and insulated from the surrounding environment, and a temperature control device for controlling the temperature of the test space. The temperature control device allows a temperature range of -80°C to +180°C, preferably a temperature range of -100°C to +200°C, to be established in the test space. In addition, the temperature control device is equipped with a cooling device comprising a cooling circuit with a refrigerant, a heat exchanger arranged in the test space, a compressor, a condenser, and an expansion element.

[0010] Document JP2007132545 in the name of TSIKISHA relates to an air conditioning system, more specifically comprising an air cooler for an air-conditioned area, the air cooler acting as an evaporator in a refrigeration circuit and controlling system components, including the air cooler, so that the air-conditioned area reaches a target temperature. The solution described in document JP2007132545 relates specifically to an air conditioning system with a control device for adjusting the temperature conditions.

[0011] Therefore, an object of the present invention is to make an environmental simulation chamber capable of operating with a refrigerant fluid having a very low GWP approaching zero.

[0012] Another object of the present invention is to produce an environmental simulation chamber that consumes less energy than existing environmental simulation chambers.

[0013] Furthermore, the invention aims at producing an environmental simulation chamber which also allows to increase the safety level of existing chambers.

[0014] Finally, the object of the invention is to propose a method of operating a chamber according to the invention which allows to achieve a high level of efficiency and safety and which is in any case superior to that of currently existing simulation chambers. Summary of the invention

[0015] These and other objects are achieved by means of an environmental simulation chamber according to claim 1 .

[0016] Specifically, the environmental simulation chamber includes a refrigeration device equipped with a refrigeration device, the refrigeration device has a closed circuit in which a refrigerant fluid circulates, and the closed circuit is equipped with at least one compressor; a cooling device for the refrigerant fluid; an expansion device and an evaporation device for the refrigerant fluid, the chamber also includes an insulating space, the sample to be tested is inserted into the insulating space, and wherein the evaporation device is suitable for adjusting the internal temperature of the insulating space, and the simulation chamber is characterized in that the refrigerant fluid is carbon dioxide.

[0017] This solution allows to achieve the proposed objectives. In fact, thanks to the presence of carbon dioxide as a refrigerant fluid, the GWP can be close to zero, ie equal to 1 within 100 years.

[0018] Furthermore, the closed circuit comprises an expansion reservoir for said carbon dioxide, operably arranged along a first length, the first length being arranged between said evaporation device and said at least one compressor, and means for allowing refrigerant fluid to fill into said expansion reservoir from said first length and for releasing refrigerant fluid from said expansion reservoir to said first length.

[0019] As will become clear from the method described below, this solution allows the compressor to be operated intermittently, i.e. shut down during partial operation of the simulated chamber, in particular in cases of partial operation of the chamber, i.e. in cases where a non-excessive level of refrigerant is required. This is achieved by reducing the opening of the expansion devices, thus allowing a lower CO2 flow rate through them than the CO2 flow rate sucked by the same compressor.

[0020] In practice, the compressor is operated intermittently at part load. In practice, the expansion reservoir is dimensioned to accommodate pressure fluctuations at the outlet of the evaporation device below a certain pressure, preferably below 8 bar, depending on the part load opening of the expansion device for temperature control.

[0021] According to the proposed solution, the simulation chamber comprises a control unit which switches the compressor on or off based on the internal temperature to be regulated in the adiabatic space, wherein the refrigerant fluid present in the expansion reservoir feeds or is filled by the closed circuit.

[0022] According to a first variant of the invention, the filling and release means comprise a connecting pipe. In this way, the expansion reservoir does not control the inflow and outflow of carbon dioxide therein, but depends on the pressure along the first length of the closed circuit, and therefore on the refrigerant fluid upstream of the same compressor.

[0023] In another embodiment, the connecting pipe comprises a first stop valve; preferably, the control unit allows or prohibits the refrigerant from flowing into / out of the expansion reservoir according to the pressure at the outlet of the evaporation device.

[0024] Alternatively, the filling / releasing device comprises a bypass circuit arranged along the first length between the evaporation device and the at least one compressor; the bypass circuit comprises a first inlet branch from the first length to the expansion reservoir and a second outlet branch from the expansion reservoir to the first length. The filling / releasing device further comprises a first shut-off valve arranged along the first branch, a second shut-off valve arranged along the second outlet branch and at least one third shut-off valve arranged along the first length between the first inlet branch and the second outlet branch. This second embodiment of the invention allows a finer control of the filling / emptying of the expansion reservoir and thus a more precise operation of the environmental simulation chamber.

[0025] Furthermore, the circuit comprises a storage reservoir of the refrigerant fluid in liquid form, which is arranged in a second length of the closed circuit between the cooling device and the expansion device.

[0026] According to another embodiment of the invention, the closed circuit comprises at least one auxiliary line, which directly or indirectly connects the closed circuit to the insulating space; the auxiliary line is provided with an inlet section for the refrigerant fluid, which is arranged along a first length of the closed circuit between the evaporation device and the at least one compressor, and an outlet section for the refrigerant fluid. The outlet section is connected to the insulating space for the carbon dioxide in gaseous form to flow into the insulating space.

[0027] In a particular embodiment of the invention, the solution is possible even without an expansion reservoir, which allows the introduction of carbon dioxide into the insulated space, thus being able to extinguish fire in the event of a fire.

[0028] Specifically, the auxiliary line includes an opening / closing valve arranged along the auxiliary line to allow or prevent the refrigerant fluid from passing along the auxiliary line.

[0029] In addition, according to a preferred embodiment of the present invention, the simulation chamber further comprises a detection device for detecting whether a fire occurs in the heat-insulating space; the detection device is operably connected to the opening / closing valve to control the opening or closing thereof. This solution allows the fire that may exist in the heat-insulating space to be automatically extinguished without the need for operator control intervention.

[0030] In another embodiment of the invention, the refrigeration device comprises another refrigeration device having another closed circuit in which another refrigerant fluid circulates; the other closed circuit is equipped with at least one other compressor, another cooling device for cooling the refrigerant fluid, another expansion device for the refrigerant fluid, and another evaporation device suitable for cooperating with the cooling device of the refrigeration device. The other refrigeration device operates in a temperature range higher than the temperature range in which the refrigeration device operates. In this case, the refrigerant fluid circulating in the closed circuit, i.e. the carbon dioxide, operates under subcritical conditions.

[0031] In another embodiment, the refrigerant fluid can also be operated under transcritical conditions, but in this case the closed circuit lacks an additional refrigeration device and, moreover, the cooling device no longer operates as a condenser. In this embodiment, the closed circuit comprises, in addition to the at least one compressor, a second high-pressure compressor connected in series with the at least one compressor, a bypass circuit for the cooling device, wherein the bypass circuit has at least one control valve for operating the bypass circuit, an intermediate throttle valve downstream of the storage reservoir and a condensing pressure control valve.

[0032] Specifically, the closed circuit further comprises a heat exchanger operatively connected to a third length of the closed circuit, the third length being located between the at least one second compressor and the refrigerant fluid storage reservoir, but downstream of the bypass circuit, and means for regulating the flow rate of the refrigerant fluid entering the heat exchanger. The heat exchanger is arranged in the thermally insulating space; preferably, the heat exchanger and the evaporation device are arranged in two separate compartments in the thermally insulating space.

[0033] This allows the same refrigeration equipment to be used to both cool and heat the insulated space.

[0034] The object is also achieved by a method for operating an environmental simulation chamber according to one or more of claims 1 to 12, comprising the following steps:

[0035] a) setting at least one temperature or at least one temperature range to be reached in the thermally insulating space;

[0036] b) starting the at least one compressor so that the refrigerant fluid circulates in the closed circuit of the refrigeration equipment;

[0037] c) regulating the opening / closing of the expansion device so as to change the flow rate of the refrigerant fluid flowing through the evaporation device according to the at least one temperature or the temperature range required in the thermally insulating space;

[0038] The refrigerant fluid is carbon dioxide.

[0039] In particular, the method further comprises a step d) of at least partially filling the expansion reservoir with the refrigerant fluid.

[0040] Furthermore, if in step c) the expansion device is operated at partial load and the at least one expansion reservoir is dimensioned to accommodate pressure fluctuations at the outlet of the evaporation device which are below a certain pressure, preferably below 8 bar, the method comprises a step e): causing the compressor to operate intermittently. In practice, the method of operating the environmental simulation chamber works advantageously, in particular when the expansion device is operated at partial load, i.e. the flow rate of the refrigerant through the expansion device is reduced compared to the flow rate sucked by the compressor. This occurs when the refrigeration load in the adiabatic space does not reach the limits of the refrigeration equipment capacity, but the temperature required by the user is preferably above -20°C. Under these conditions, thanks to the presence of the expansion reservoir, it is possible to cause the compressor to operate intermittently, i.e. by switching it off and on again, while still maintaining an extremely efficient level of cooling control in the adiabatic space. In known simulation chambers, such as patent WO2020012348 in the name of the applicant, the compressor is always kept on, and its operation consumes a lot of electrical energy.

[0041] Furthermore, said step e) comprises a step e1) of reducing the flow rate of the refrigerant fluid flowing through said expansion device to a value lower than the flow rate sucked by said at least one compressor, in this way reducing the suction pressure of said at least one compressor to a pressure value that shuts it down, a step e2) of feeding said expansion reservoir with said fluid flowing out of said evaporation device until the pressure of said expansion reservoir has risen to a first pressure value, which depends on the desired temperature or temperature range in said adiabatic space and is equal to the pressure at which said at least one compressor starts sucking refrigerant fluid from said expansion reservoir in said step e1), and a step e3) of restarting the operation of said compressor when said first pressure in said reservoir is exceeded, said steps e1), e2) and e3) being repeated periodically. This solution has the advantage of being able to operate with a compressor that operates intermittently, while still having excellent temperature control capabilities in the adiabatic space.

[0042] It should be noted that when the compressor is shut down, the refrigerant flow through the same compressor is blocked, therefore the refrigerant fluid continuing through the expansion device and therefore also through the evaporation device, accumulates downstream of these devices, increasing the pressure in the expansion reservoir.

[0043] The operation of the above described simulation chamber allows saving energy for the overall operation of the environmental simulation chamber.

[0044] This operating mode is achieved by Figure 1 The solution shown is implemented.

[0045] As an alternative to the above-mentioned operating method, the following solution is adopted, wherein the filling / releasing device comprises a first stop valve arranged along the first branch, a second stop valve arranged along the second outlet branch, and at least one third stop valve arranged along the first length between the first inlet branch and the second outlet branch, i.e., Figure 2 In the embodiment shown in, the step e) comprises a step e1'), reducing the flow rate of the refrigerant fluid through the expansion device to a value lower than the suction of the at least one compressor, a step e2'), closing the third stop valve and the first stop valve when a first suction pressure of the compressor is reached, and opening or keeping open the at least one second stop valve, the first suction pressure depending on the required temperature or temperature range in the insulating space and being equal to the pressure at which the at least one compressor starts to suck refrigerant fluid from the expansion storage in the step e1'), and a step e3'), shutting down the at least one compressor when a pressure value causing it to shut down is reached. The method further includes step e4'), if during step e2') and / or step e3'), the pressure of the refrigerant fluid between the first stop valve or the third stop valve and the evaporation device is higher than the second suction pressure of the compressor 2, and the second suction pressure of the compressor 2 is higher than the first suction pressure, then reopen the first stop valve, step e5'), if during step e2') and step e3'), the pressure of the refrigerant fluid between the first stop valve or the third stop valve and the evaporation device drops to a value lower than the first suction pressure of the compressor, then close the first stop valve, and step e6'), when the pressure in the expansion storage is higher than the first pressure, restart the compressor. Finally, steps e1') to e6') are repeated in a cyclic manner.

[0046] This solution ensures a higher level of control compared to a closed circuit without the bypass circuit of the expansion reservoir and the three shut-off valves mentioned above.

[0047] Furthermore, still in the case of a solution in which the filling / releasing device comprises a first stop valve arranged along the first branch, a second stop valve arranged along the second branch and at least one third stop valve arranged along the first length between the first inlet branch and the second outlet branch, the method therefore comprises a step f) of keeping the second stop valve and the third stop valve open and keeping the first stop valve closed, so that at least when the flow rate sucked by the at least one compressor is equal to the flow rate through the expansion device (i.e. in the case of full load of the model chamber), or for a closed ambient simulation chamber (zero load), the refrigerant fluid present in the expansion storage balances the increase in specific volume of the refrigerant gas present in the closed circuit, and / or allows any undesirable pressure increase within the closed circuit to be reduced.

[0048] In addition, still in the case of a solution in which the filling / releasing device includes a first stop valve arranged along the first branch, a second stop valve arranged along the second outlet branch, and at least one third stop valve arranged along the first length between the first inlet branch and the second outlet branch, the step a) includes step a1), rapidly increasing the requirement for the required refrigeration load (i.e., the booster operating conditions); in this case, the method further includes step h), reducing the pressure in the expansion storage to a minimum pressure value, preferably equal to the minimum suction pressure value of the at least one compressor, and after step h), opening and keeping the first stop valve and the expansion device open.

[0049] Furthermore, in the case of a solution in which the filling / releasing means comprises a first shut-off valve arranged along the first branch, the step a) comprises a step a1) of rapidly increasing the demand for the required refrigeration load (i.e., booster operating conditions); in this case, the method further comprises a step h) of reducing the pressure in the expansion reservoir to a minimum pressure value, preferably equal to the minimum suction pressure value of the at least one compressor. Wherein the step h) is performed before, after and simultaneously with the step a1), the method comprises a step r) of keeping the first shut-off valve and the expansion means open.

[0050] In addition, step r) continues until the temperature in the insulating space is higher than the value of the evaporation temperature of the refrigerant fluid in the evaporation device, preferably, the temperature in the chamber is 10K (Kelvin) higher than the evaporation temperature, or the suction pressure of the at least one compressor has reached the maximum operating condition expected by the operating conditions of the at least one compressor, and the at least one stop valve and / or the at least one second stop valve are closed; the storage reservoir of the refrigerant fluid and the expansion reservoir are sized so that the refrigerant fluid is not exhausted during step r).

[0051] In the case of a circuit in which the refrigerant fluid circulates under transcritical conditions, a step l) of making the refrigerant fluid flow along said heat exchanger is then carried out simultaneously with or independently of said step h).

[0052] In addition, the method also includes step m), controlling the opening of the opening / closing valve to allow the refrigerant fluid to pass along the auxiliary pipeline, and step n), connecting the closed-loop fluid to the insulating space with the aid of the auxiliary pipeline, wherein the auxiliary pipeline is provided with an inlet section for the refrigerant fluid and an outlet section for the refrigerant fluid, the inlet section being arranged between the evaporation device and the at least one compressor along the first length of the closed loop; the outlet section being connected to the insulating space so that carbon dioxide flows into the insulating space in a gaseous form.

[0053] In addition, the step m) is preceded by a step o) of detecting whether there is a fire in the insulation space. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Some specific embodiments of the present invention will now be described, by way of non-limiting examples only, with reference to the accompanying drawings, in which:

[0055] Figure 1 is a schematic diagram of an environmental simulation chamber according to a first embodiment of the present invention, wherein the refrigerant fluid operates under subcritical conditions;

[0056] Figure 2 is a schematic diagram of an environmental simulation chamber according to a second embodiment of the present invention, wherein the refrigerant fluid operates under subcritical conditions;

[0057] Figure 3 is a schematic diagram of an environmental simulation chamber according to a third embodiment of the present invention, wherein the refrigerant fluid operates under transcritical conditions;

[0058] Figure 4 is a schematic diagram of an environmental simulation chamber according to another embodiment of the present invention, wherein the refrigerant fluid operates under subcritical conditions. DETAILED DESCRIPTION

[0059] Figure 1 An environmental simulation chamber 100 is shown in a simplified manner, comprising a refrigeration device 10 equipped with a refrigeration device 1 having a closed circuit C in which a refrigerant fluid circulates. The closed circuit C1 is equipped with at least one compressor 2, in particular with a piston, a cooling device 3 for the refrigerant fluid, an expansion device 4 for the refrigerant fluid and an evaporation device 5. It should be noted that embodiments comprising two or more compressors arranged in series or in stages still fall within the scope of protection of the present invention.

[0060] The chamber 100 also comprises an insulating space 20 in which a sample 21 to be tested is inserted and in which the evaporation device 5 cooperates with said expansion device 4, adapted to regulate the temperature in the insulating space 20. Advantageously, the refrigerant fluid used in the refrigeration device 1 is carbon dioxide.

[0061] This solution allows the GWP value of such an environmental simulation chamber 100 to be reduced to 1, thus allowing a huge environmental benefit to be achieved.

[0062] Still according to the present description and Figure 1 In the first embodiment shown in , the closed circuit C further comprises an expansion reservoir 30 for carbon dioxide, which is operably arranged along the first length T, positioned between the evaporation device 5 and the compressor 2, and a device 6 for allowing the refrigerant fluid to be filled into the expansion reservoir 30 from the first length T and allowing the refrigerant fluid to be released from the expansion reservoir 30 to the first length T.

[0063] In particular, the compressor 2 is operated intermittently at part load due to the presence of the expansion reservoir 30. In practice, the dimensions of this expansion reservoir 30 are in fact designed to contain the pressure fluctuations at the outlet of the evaporation device 5 to a level below a certain pressure, preferably below 8 bar, depending on the part load opening of the expansion device 4 for temperature control.

[0064] In particular, the chamber 1 comprises a control unit which switches the compressor 2 on and off based on the internal temperature to be regulated in the adiabatic space 30. Thus, the refrigerant fluid present in the expansion reservoir 30 feeds the closed circuit C, or is fed by the closed circuit C, since it is filled by the expansion device 5 during intermittent operation of the compressor 2.

[0065] Still based on Figure 1 In the embodiment described in , the filling and releasing device 6 comprises a connecting duct 61 between the expansion reservoir 30 and the aforementioned first length T positioned between the evaporation device 5 and the compressor 2 .

[0066] The presence of the pressure reservoir 30 allows the compressor 2 to be operated intermittently at part load, if it is specially designed to contain limited pressure fluctuations on the evaporation device 4, preferably not higher than 8 bar, depending on the part load opening of the expansion device 4 for temperature control, up to 50%, without exceeding the number of starts per minute allowed by the manufacturer of the compressor 2. In a conventional environmental simulation chamber with a conventional refrigerant, the compressor is always kept in motion due to the load limitation and the operation of the refrigeration equipment is achieved by a so-called hot gas bypass pipe or line (see also the description below).

[0067] It should be emphasized that "operation of the compressor 2 at part load" means that, within the adiabatic space 20, a temperature to be used is sought which is not the maximum minimum limit achievable by the refrigeration device 10, but which results in, for example, a maximum opening of 50% of the expansion device 4. The expansion device 4 is provided with, for example, a throttle valve, by the opening of which the flow rate of the refrigerant fluid reaching the evaporation device 5 is controlled, thus ultimately allowing the temperature within the adiabatic space 20 to be regulated. Part load operation therefore means operation which allows reaching a temperature higher than the lowest limit achievable.

[0068] On the other hand, the presence of a refrigerant fluid such as carbon dioxide allows the use of an expansion accumulator 30 of limited dimensions, compared to the expansion accumulators that would be used in a closed circuit in which a known refrigerant such as R449 circulates, on the contrary. In fact, with this refrigerant, the specific gas volume produced is much higher than when using carbon dioxide, and therefore, in these systems using R449, the expansion accumulator would take up a lot of space to ensure similar operating conditions. Therefore, in refrigeration equipment of the known art, i.e. refrigeration equipment operating with R449, such an expansion accumulator is never used.

[0069] also, Figure 1 Also shown along the closed circuit C is a hot gas bypass line 35 with a corresponding valve 36 which allows the refrigerant fluid to flow through the line 35 in case of partial load operation of the refrigeration device 1 instead of through the expansion device 4 and the evaporation device 5. In this case, the compressor 2 operates uninterruptedly, i.e. continuously, and the temperature in the adiabatic chamber 20 is close to a minimum value.

[0070] Still refer to Figure 1, the chamber comprises at least one auxiliary line 50, which directly connects the closed circuit C to the insulated space 20. The auxiliary line 50 is provided with: an inlet section 51 for the refrigerant fluid, which is arranged along the first length T of the closed circuit C between the evaporation device 5 and the compressor 2; an outlet section 52 for the refrigerant fluid; and an opening / closing valve 55 to allow or not allow the passage of carbon dioxide along the auxiliary line 50. The outlet section 52 is connected to the insulated space 20 for flowing carbon dioxide in gaseous form into the insulated space. Therefore, this solution allows the real fire extinguisher to be always connected inside the insulated space 20.

[0071] It should be noted that this auxiliary line 50 can also be connected indirectly to the circuit C if connected, for example, to the evaporation reservoir 30 .

[0072] In another embodiment not shown here, the chamber 100 may include the auxiliary line 50, but the refrigeration device 1 may be without the expansion reservoir 30, without departing from the scope of protection of the present invention.

[0073] Furthermore, the chamber 100 also comprises means 80 for detecting the ignition of a flame in the insulating space 20. In particular, these detection means 80 are operatively connected to the opening / closing valve 55 for controlling its opening or closing. Thus, in the event of a flame being detected or a fire starting in the insulating space 20, the valve 55 will be immediately controlled to open to allow part of the carbon dioxide flow rate circulating in the closed circuit C to reach the insulating space and thus extinguish the fire.

[0074] Still according to this first embodiment, the refrigeration device 1 comprises another refrigeration device 10', which has another closed circuit C', in which another refrigerant fluid circulates. The other closed circuit C' is equipped with another compressor 2', another cooling device 3' for the refrigerant fluid, another expansion device 4' for the refrigerant fluid, and another evaporation device 5' suitable for cooperating with the cooling device 3 of the refrigeration device 10 of the closed circuit C of the refrigeration device 1. The operating temperature range of the other refrigeration device 10' is higher than the operating temperature range of the refrigeration device 10. In addition, the refrigerant fluid used in the other refrigeration device 10' is R449.

[0075] In this case, the refrigerant fluid of the refrigeration device 10, ie carbon dioxide, operates under subcritical conditions, typically the refrigerant fluid has a temperature below 20° C. In this case, the cooling device 3 operates in the same way as a normal operation of the condenser.

[0076] exist Figure 2 In the embodiment, Figure 1The only difference of the embodiment of the invention is that the filling / releasing device 6 this time comprises a bypass circuit C1 arranged along the first length T between the evaporation device 5 and the compressor 2. The bypass circuit C1 comprises a first inlet branch 41 from the first length to the expansion reservoir 30 and a second outlet branch 42 from the expansion reservoir 30 to the first length T. The filling / releasing device 6 further comprises a first shut-off valve 43 arranged along the first branch 41, a second shut-off valve 44 arranged along the second outlet branch 42 and a third shut-off valve 45 arranged along the first length T between the first inlet branch 41 and the second outlet branch 42.

[0077] The presence of this bypass circuit C1 and the shut-off valves 43, 44 and 45 allows the operation of the refrigeration device 10 to be finely controlled according to the temperature control requirements in the insulating space 20, however, this will become clear from the method of operation of the chamber 100 explained below.

[0078] exist Figure 4 In the embodiment, Figure 1 The embodiment of the present invention differs in that the filling / releasing device 6 comprises a connecting pipe 61, which in turn comprises a first shut-off valve 43. The control unit is adapted to open or close the first valve 43 according to the pressure at the outlet of the evaporation device 5, so as to allow or not allow the refrigerant fluid to flow into / out of the expansion reservoir 30.

[0079] In the above description and Figure 1 , 2 In the embodiment shown in FIGS. 4 and 5 , the circuit C further comprises a storage reservoir 70 of the refrigerant fluid in liquid form and this storage reservoir 70 is arranged in a second length T2 of the closed circuit C (operatively) between the cooling device 3 and the expansion device 4 .

[0080] However, in the case where the refrigerant fluid circulating in the circuit C operates under transcritical conditions, there is no further refrigeration device 10 ′ and the cooling device 3 no longer operates as in a condenser. Figure 3 In the embodiment shown, relative to Figure 1 , 2 and the circuit C shown in 4, in addition, in a known manner, there is a second high-pressure compressor 110; a bypass circuit 112 for the cooling device 3, which is equipped with a control valve 113 for starting the bypass circuit 112; an intermediate throttle valve 114 and a condensing pressure control valve 115 arranged downstream of the storage reservoir 70.

[0081] The second compressor 110 is preferably also of the piston type.

[0082] The intermediate throttle valve 114 is operably arranged between the storage reservoir 70 and the second high-pressure compressor 110 and, similar to the hot gas bypass line 35 and the corresponding valve 36, allows the coolant flow to pass through this line instead of through the expansion device 4 and the evaporation device 5 in the case of partial load operation of the refrigeration device 1.

[0083] In addition, the condensing pressure control valve 115 arranged upstream of the storage reservoir 70 and downstream of the cooling device and the bypass circuit 112 has a function of allowing throttling of the refrigerant fluid, thereby adjusting the condensing pressure in the storage reservoir 70 .

[0084] The bypass circuit 112 allows bypassing the cooling device 3 so that the refrigerant fluid is not cooled but maintained at a temperature required for other applications, as will become apparent in the following paragraphs.

[0085] In this embodiment, the closed circuit C further comprises a heat exchanger 200 operatively coupled to another length T3 of the closed circuit C, the other length T3 being located between the second high-pressure compressor 110 and the storage reservoir 70, but downstream of the bypass circuit 112. The closed circuit C further comprises means 205, 206 for regulating the flow rate of the refrigerant fluid entering the heat exchanger 200. The heat exchanger 200 is arranged in the thermally insulating space 20.

[0086] These regulating means comprise a three-way valve 205 to divert the flow of refrigerant gas, i.e. carbon dioxide, from the second high-pressure compressor 110 in the direction of the exchanger 200, and a non-return valve 206 leaving the exchanger 200. The three-way valve is operatively arranged downstream of the bypass circuit 112. When the three-way valve 205 for the passage of the high-temperature refrigerant fluid in the heat exchanger 200 operates, the control valve 113 for the operation of the bypass circuit 112 is simultaneously activated, in which way the cooling device 3 is bypassed.

[0087] In addition, Figure 3 In the illustrated embodiment, the heat exchanger 200 and the evaporation device 5 are arranged in two separate compartments within the insulating space 20 .

[0088] It should be noted that although Figure 3 The illustrated embodiment of the simulation chamber 100 provides Figure 2The presence of a filling / releasing device 6 of the type shown, i.e., wherein a bypass circuit C1 is provided which is arranged along a first length T between the evaporation device 5 and the compressor 2, and wherein the bypass circuit C1 comprises a first inlet branch 41 and a second outlet branch 42 from the expansion reservoir 30 to the first length T, and wherein the filling / releasing device 6 further comprises a first shut-off valve 43 arranged along the first branch 41, a second shut-off valve 44 arranged along the second outlet branch 42 and a third shut-off valve 45 arranged between the first inlet branch 41 and the second outlet branch 42 along the first length T, but these filling / releasing devices 6 are Figure 1 In an embodiment of the type shown, the presence of a conduit 61 is provided, or Figure 4 Embodiments of the type shown, in which the conduit 61 comprises a first shut-off valve 43, nevertheless fall within the scope of protection of the present invention.

[0089] The following will describe Figures 1 to 4 The operating mode of chamber 100 is shown.

[0090] Specifically, the operating method of the environmental simulation chamber 100 includes the following steps:

[0091] a) setting the temperature or temperature range to be achieved in the insulating space 20;

[0092] b) activating the compressor 2 so that the refrigerant fluid circulates in the closed circuit C of the refrigeration device 10;

[0093] c) regulating the opening / closing of the expansion device 4, thereby changing the flow rate of the refrigerant fluid flowing through the evaporation device 5 according to the desired temperature or temperature range in the thermal insulation space 20;

[0094] The refrigerant fluid circulating in loop C is carbon dioxide.

[0095] In particular, the method comprises a step d) of at least partially filling the expansion reservoir 30 with a refrigerant fluid to compensate for any rapid demand by the user for a temperature change, or to allow the chamber 100 to operate while keeping part of the compressor 2 operating in an idle state. Such an activity cannot be achieved using prior art refrigerant fluids such as R449, because, as mentioned above, the specific volume values ​​of this known gas are much greater than those of carbon dioxide, and therefore any expansion reservoir would be too large to use.

[0096] Furthermore, if in step c) the expansion device 4 is operated at partial load and the expansion reservoir 30 is dimensioned to contain the pressure fluctuations at the outlet of the evaporation device 5 below a certain pressure, preferably below 8 bar, the method comprises a step e) of operating the compressor intermittently, i.e. successively shutting off or starting the compressor 2 when a certain thermodynamic condition of the refrigerant fluid is reached. The filling and emptying of the expansion reservoir 30 thus depends on the temperature to be maintained in the adiabatic space 20 and on the characteristics of the compressor 2, i.e. the minimum operating pressure that can be reached and the number of activations / deactivations per minute that the compressor can withstand without risk of failure.

[0097] It should be emphasized that “the expansion device 4 operates at part load” means that, within the adiabatic space 20, the temperature sought to be used is not the maximum minimum limit that the refrigeration device 10 can reach, but results in a maximum opening of 50% of the expansion device 4. The expansion device 4 provides for example the presence of a throttle valve, through whose opening the flow rate of the refrigerant fluid reaching the evaporation device 5 is controlled, thus ultimately allowing the temperature prevailing within the adiabatic space 20 to be regulated.

[0098] Specifically, in Figure 1 In the case of an embodiment of the present invention, therefore without the bypass circuit C1, step e) of the method comprises a step e1): reducing the flow rate of the refrigerant fluid through the expansion device 4 to a value lower than the flow rate of the refrigerant fluid sucked by the compressor 2, thereby reducing the suction pressure of the compressor 2 to a pressure value Ps that shuts it down; a step e2): feeding the expansion reservoir 30 by the fluid flowing out of the evaporation device 5 until the pressure of the expansion reservoir 30 has risen to a first pressure value P1, which depends on the desired temperature or temperature range in the adiabatic space 20 and is equal to the suction pressure at which the compressor 2 starts to suck the refrigerant fluid from the expansion reservoir 30 in step e1); and a step e3): restarting the operation of the compressor 2 when the first pressure value P1 in the expansion reservoir 30 is exceeded. Steps e1), e2) and e3) are repeated in a cyclic manner.

[0099] The shut-down of the compressor 2 and in any case the normal operation of the chamber 100 allow considerable savings in the energy costs of the chamber 100 , not to mention that the compressor 2 will work much less than usual, thus also reducing wear and damage to this component.

[0100] In fact, once a temperature is determined / set / selected inside the adiabatic space 20, for example -15°C (which corresponds approximately to the evaporation temperature of the refrigerant fluid inside the evaporation device 4 -25°C), so as to operate at partial load, that is, under non-extreme conditions, this implicitly determines the operating step e1 of the method). At this point, the flow rate of the refrigerant fluid flowing through the expansion device 4 is less than the flow rate fed by the compressor 2, and therefore, the pressure of the refrigerant fluid begins to be lower and lower downstream of the evaporation device 4. During this step, the flow of refrigerant fluid coming out of the evaporation device 4 reaches the compressor 2 until a certain pressure is reached. In fact, it should be remembered that once the test temperature is set inside the adiabatic space 20, the value of the thermodynamic pressure of the refrigerant fluid across the circuit C is known, in particular the pressure P1 at the inlet of the compressor 2 (at suction). Therefore, the pressure P1 or the first pressure is uniquely determined by the temperature sought in the adiabatic space 20. For example, in the example provided herein, the temperature of the adiabatic space 20 is -15°C, then the first pressure P1 corresponds to 17 bar.

[0101] Once the same compressor is selected, the pressure value Ps is determined for shutting down compressor 2. In this case, for example, the suction pressure for shutting down compressor 2 is 8.5 bar.

[0102] Therefore, during step e1), if the pressure of the refrigerant fluid upstream of the compressor 2 still drops below the value of the first pressure P1 (as described above, this pressure can be determined once the pressure is set in the adiabatic space 20 and can therefore vary according to this value), the compressor 2 continues to suck refrigerant gas at this point, not from the outlet of the evaporation device 5, but mainly from the expansion reservoir 30, the pressure of which is greater than the gas pressure at the outlet of the evaporation device 5. The compressor 2 does not stop until the pressure drops below the Ps value (e.g. 8.5 bar).

[0103] If the compressor 2 has reached the closing value Ps, until the pressure in the expansion storage 30 gradually rises to the value of the first pressure value P1 due to the opening action of the expansion device 4, the chamber 100 can continue to operate with excellent regulation characteristics when the compressor 2 is closed, which significantly saves energy by more than 50% compared with the traditional chamber.

[0104] However, the expansion reservoir 30 of the refrigerant fluid is dimensioned according to the size of the storage reservoir 70 of the refrigerant fluid in liquid form in order to prevent a lack of supply of liquid refrigerant fluid to the expansion device 4 when the compressor 2 is switched off.

[0105] Once the pressure in the expansion reservoir 30 rises above the first pressure P1 (step e3), the compressor 2 is restarted. Then, the cycle of switching on and off is continuously repeated.

[0106] Obviously, the number of cycles of turning on and off the compressor 2 cannot exceed the limit value specified by the manufacturer, otherwise the compressor 2 may fail.

[0107] exist Figure 2 In the case of an embodiment, the filling / releasing device includes a first stop valve 43 arranged along the first branch 41, a second stop valve 44 arranged along the second outlet branch 42, and a third stop valve 45 arranged along the first length T between the first inlet branch 41 and the second outlet branch 42. In this case, the same pressure P1, Ps and temperature values ​​as in the previous example are maintained, that is, the pressure P1, Ps and temperature in the insulating space 20 are 17 bar, 8.5 bar and -15°C respectively, and step e) of the method now includes: step e1'): reducing the flow rate of the refrigerant fluid passing through the expansion device 4 to a value lower than the flow rate sucked by the compressor 2; step e2'): when a first suction pressure P1' of the compressor 2 is reached (which corresponds to the same first pressure P1 as in the previous case, i.e. 17 bar), closing the third stop valve 45 and the first stop valve 43 and opening the second stop valve 44 or keeping the second stop valve 44 open, the first suction pressure P1' being determined according to the required temperature or temperature range in the insulating space 20 and being equal to the pressure at which the compressor 2 starts to suck refrigerant fluid from the expansion storage 30 (rather than the expansion device 5) during step e1'); and step e3'): shutting down the compressor 2 when the pressure value Ps that causes the compressor 2 to shut down is reached. The method further comprises: step e4'): if during step e2') and / or e3'), the pressure of the refrigerant fluid between the first stop valve 43 or the third stop valve 45 and the evaporation device 5 is higher than the second suction pressure P2' (e.g., 17.5 bar), reopening the first stop valve 43; step e5'): if during step e2') and / or e3'), the pressure of the refrigerant fluid between the first stop valve 43 or the third stop valve 45 and the evaporation device 5 decreases to a value lower than the first suction pressure P1' of the compressor 2, closing the first stop valve 43; and step e6'): at least when the pressure in the expansion storage 30 is higher than the first pressure P1' (i.e., lower than 17 bar), reactivating the compressor 2. Finally, steps e1') to e6') are repeated in a cyclic manner.

[0108] In addition, Figure 2In the embodiment of the invention, in the steady state, i.e. in the case of full load operation, the method comprises step f) of keeping the second stop valve 44 and the third stop valve 45 open and keeping the first stop valve 43 closed, so that at least when the flow rate sucked by the compressor 2 is equal to the flow rate through the expansion device 4, or when the environmental simulation chamber 100 is closed (and therefore the compressor 2 is closed), the refrigerant fluid present in the expansion reservoir 30 compensates for the increase in the specific volume of the refrigerant gas present in the closed circuit C and / or allows to reduce any unwanted pressure increase in the closed circuit C. This operation takes place when step e) of the above method is just not required, i.e. the compressor 2 is operated intermittently, since the required flow rate load of the refrigerant fluid is only partial and therefore the required temperature in the adiabatic space 20 is not extreme (i.e. below -20°C).

[0109] therefore, Figure 2 The specific operating mode of the chamber 100 shown in the figure, wherein the filling / releasing device includes a first stop valve 43 arranged along the first branch 41, a second stop valve 44 arranged along the second outlet branch 42, and a third stop valve 45 arranged along the first length T between the first inlet branch 41 and the second outlet branch 42, and it is stipulated that step a) of the method includes: step a1), the requirement for rapidly increasing the required refrigeration load, that is, what a person skilled in the art calls the "booster" state, and the method also includes step h), reducing the pressure in the expansion storage 30 to a minimum pressure value, preferably equal to the minimum suction pressure value Ps of the compressor 2, and after step h), opening and keeping the first stop valve 42 and the expansion device 4 fully open.

[0110] In addition, Figure 4 Another operating mode of the chamber 100 is shown in FIG. 1 , whereby the filling / releasing device comprises a first stop valve 43 arranged along the connecting pipe 61, step a) of the method is provided to comprise a step a1) of rapidly increasing the demand for the required refrigeration load, i.e. the so-called "booster" state by those skilled in the art, and the method further comprises a step h) of reducing the pressure in the expansion reservoir 30 to a minimum pressure value, preferably equal to the minimum suction pressure value Ps of the compressor 2. This step h) precedes step a1), i.e. prepares for the "booster" step, i.e. rapidly requiring a temperature drop in the adiabatic space 20. After step h) and simultaneously with step a1), the method comprises a step r) of keeping the first stop valve 43 and the expansion device 4 open.

[0111] According to the "booster" operating mode, step r) is continued until the temperature in the adiabatic space 20 reaches a value above the evaporation temperature of the refrigerant fluid in the evaporation device 5, preferably this temperature in the adiabatic space 20 is 10° C. above the evaporation temperature, or the suction pressure of the compressor 2 has reached the maximum operating conditions provided for the operating conditions of the same compressor 2, and the first shut-off valve 43 (at Figure 4 In the case of the embodiment shown in the figure) is closed, or the first stop valve 43 and the second stop valve 44 are closed (in Figure 2 In this case, in order to enable step r) to be carried out, the storage reservoir of liquid refrigerant 70 and the expansion reservoir 30 must be sized so that during step r) the liquid phase refrigerant fluid is not depleted to prevent a lack of liquid refrigerant fluid at the expansion device 4 during the action of the booster.

[0112] exist Figure 3 In the case of the embodiment shown, and in the case that the refrigeration device 10 requests a booster, it is the case that, simultaneously with step h) or independently of step h), step l) of causing the refrigerant fluid to flow along the heat exchanger 200 is performed.

[0113] In the above Figures 1 to 4 In any of the embodiments shown in , the method includes step m), controlling the opening of the opening / closing valve 55 to allow the refrigerant fluid (i.e., carbon dioxide) to pass along the auxiliary pipeline, and step n), connecting the closed loop C fluid to the insulating space 20 by means of the auxiliary pipeline 50. The auxiliary pipeline 50 is provided with an inlet section 51 for the refrigerant fluid and an outlet section 52 for the refrigerant fluid, the inlet section 51 being arranged along the first length T of the closed loop C between the evaporation device 5 and the compressor 2. The outlet section 52 is connected to the insulating space 20 for flowing carbon dioxide in gaseous form into the insulating space 20.

[0114] In addition, step m) is preceded by step o), and step o) detects the ignition of fire in the insulation space 20 as a condition for the occurrence of step m).

[0115] It should be noted that these steps m), n) and o) can be performed independently of steps e) to h) or in combination with steps a) to d) of the method.

Claims

1. An environmental simulation chamber (100), comprising: A refrigeration device equipped with a refrigeration device (10), the refrigeration device (10) having a closed circuit (C) in which a refrigerant fluid circulates, the closed circuit (C) being equipped with at least one compressor (2); a cooling device (3) for the refrigerant fluid; an expansion device (4) and an evaporation device (5) for the refrigerant fluid, the chamber (100) further comprising an insulating space (20), a sample to be tested (21) being inserted into the insulating space (20), and wherein the evaporation device (5) is suitable for adjusting the internal temperature of the insulating space (20), the simulation chamber being characterized in that the refrigerant fluid is carbon dioxide.

2. The chamber (100) according to claim 1, characterized in that The closed circuit further comprises an expansion reservoir (30) for the carbon dioxide, the expansion reservoir being operatively arranged along a first length (T), the first length being arranged between the evaporation device (5) and the at least one compressor (2), and means (6) for allowing refrigerant fluid to fill the expansion reservoir (30) from the first length (T) and for releasing refrigerant fluid from the expansion reservoir (30) to the first length (T).

3. The chamber according to claim 2, characterized in that The compressor (2) is operated intermittently under partial load conditions.

4. The chamber according to claim 2 or 3, characterized in that It comprises at least one control unit which switches the compressor (2) on or off based on the internal temperature to be regulated in the insulating space, the refrigerant fluid present in the expansion reservoir (30) feeding the circuit (C) and / or being filled by the circuit (C).

5. Chamber (100) according to one or more of claims 2 to 4, characterized in that The filling and releasing device (6) comprises a connecting pipe (61).

6. The chamber (100) according to claim 5, characterized in that The connecting pipe (61) includes a first stop valve (43), and preferably the control unit opens or closes the first valve (43) according to the pressure at the outlet of the evaporation device (5) to allow or prohibit the refrigerant fluid from flowing into / out of the expansion storage device (30).

7. Chamber (100) according to one or more of claims 2 to 6, characterized in that The circuit (C) also comprises a storage reservoir (70) of the refrigerant fluid in liquid form, the storage reservoir being arranged in a second length (T2) of the closed circuit between the refrigeration device (3) and the expansion device (4).

8. Chamber (100) according to one or more of claims 1 to 7, characterized in that The invention comprises at least one auxiliary pipeline (50), which directly or indirectly connects the closed circuit (C) to the insulating space (20), and the auxiliary pipeline (50) is provided with: an inlet section (51) for the refrigerant fluid, the inlet section (51) being arranged between the evaporation device (5) and the at least one compressor (2) along a first length (T) of the closed circuit (C); an outlet section (52) for the refrigerant fluid; and an opening / closing valve (55) for allowing / preventing the refrigerant fluid from passing along the auxiliary pipeline, the outlet section (52) being connected to the insulating space (20) so that carbon dioxide in gaseous form flows into the insulating space (20).

9. The chamber (100) according to claim 8, characterized in that It also includes a detection device (80) for detecting a fire in the heat-insulating space (20), and the detection device (80) is operably connected to the opening / closing valve (55) to control the opening or closing thereof.

10. Chamber (100) according to one or more of claims 1 to 9, characterized in that The refrigeration device comprises another refrigeration device (10'), the other refrigeration device (10') having another closed circuit (C'), another refrigerant fluid circulates in the other closed circuit, the other closed circuit (C') is equipped with at least one other compressor (2'), another cooling device (3') for the refrigerant fluid, another expansion device (4') for the refrigerant fluid and another evaporation device (5') suitable for cooperating with the cooling device (3) of the refrigeration device (10), and the other refrigeration device (10') operates within a temperature range higher than the operating temperature range of the refrigeration device (10).

11. Chamber (100) according to one or more of claims 1 to 9, characterized in that The closed loop (C) also includes at least one second high-pressure compressor (110) arranged in series with the at least one compressor (2), a bypass loop (112) for the cooling device (3), the bypass loop having at least one control valve (113) for operating the bypass loop (112), an intermediate throttle valve (114) and a condensing pressure control valve (115) located downstream of the storage reservoir (70), and the intermediate throttle valve (114) is operably arranged between the storage reservoir (70) and the second compressor (110).

12. The chamber (100) according to claim 1, characterized in that The closed circuit also includes a heat exchanger (100), which is operably connected to a third length (T3) of the closed circuit (C), the third length (T3) being located downstream of the bypass circuit (112), between the at least one second compressor (110) and the storage reservoir (70) of the refrigerant fluid, and a device (205, 206) for adjusting the flow rate of the refrigerant fluid entering the heat exchanger, the heat exchanger (200) being arranged in the insulating space (20), preferably, the heat exchanger (200) and the evaporation device (5) are arranged in two independent compartments present in the insulating space (20).

13. Method for operating an environmental simulation chamber according to one or more of claims 1 to 12, comprising the following steps: a) setting at least one temperature or at least one temperature range to be obtained in the thermally insulating space; b) starting the at least one compressor (2) so that the refrigerant fluid circulates in the closed circuit (C) of the refrigeration device (10); c) regulating the opening / closing of the expansion device (4) so ​​as to change the flow rate of the refrigerant fluid flowing through the evaporation device (5) according to the at least one temperature or the temperature range required in the thermal insulation space; Wherein, the refrigerant fluid is carbon dioxide.

14. The method according to claim 13, characterized in that It comprises the step d) of at least partially filling the expansion reservoir (30) with the refrigerant fluid.

15. The method according to claim 14, characterized in that If in step c) the expansion device is operated at part load and the at least one expansion reservoir (30) is dimensioned to accommodate pressure fluctuations at the outlet of the evaporation device which are below a certain pressure, preferably below 8 bar, the method comprises a step e) of operating the compressor intermittently.

16. The method according to claim 15, characterized in that The step e) comprises: step e1), reducing the flow rate of the refrigerant fluid flowing through the expansion device (4) to a value lower than the flow rate sucked by the at least one compressor (2), thereby reducing the suction pressure of the at least one compressor to a pressure value (Ps) that shuts it down; step e2), feeding the expansion reservoir (30) with the fluid flowing out of the evaporation device until the pressure of the expansion reservoir (30) rises to a first pressure value (P1), the first pressure value (P1) depending on the required temperature or temperature range in the adiabatic space and being equal to the suction pressure of the at least one compressor (2) when it starts to suck refrigerant fluid from the expansion reservoir (30) in the step e1); and step e3), restarting the operation of the compressor when the first pressure value (P1) in the reservoir is exceeded, wherein steps e1), e2) and e3) are repeated periodically.

17. A method according to at least claim 13, wherein: The filling / releasing device (6) comprises a first stop valve (43) arranged along the connecting pipe (61), characterized in that step a) comprises step a1), rapidly increasing the demand for the required refrigeration load, and wherein the method further comprises step h), reducing the pressure in the expansion storage (30) to a minimum pressure value, preferably equal to the minimum suction pressure value (Ps) of the at least one compressor (2), wherein step h) is before step a1), and after step h) and simultaneously with step a1), the method further comprises step r), keeping the first stop valve (43) and the expansion device (4) open.

18. The method according to claim 17, characterized in that Said step r) is continued until the temperature in said insulating space reaches a value higher than the evaporation temperature of the refrigerant fluid in said evaporation device, preferably said temperature in said chamber is 10K higher than said evaporation temperature, or said suction pressure of said at least one compressor (2) has reached the maximum operating condition expected by the operating conditions of said at least one compressor (2), and said at least one shut-off valve (43) is closed, said storage reservoir (70) and said expansion reservoir (30) of said refrigerant fluid are sized so that during said step r) the liquid phase refrigerant fluid is exhausted.

19. The method according to one or more of claims 13 to 18, in a simulation chamber according to at least claim 12, and wherein, The refrigerant fluid circulates in the closed circuit under transcritical conditions, characterized in that, simultaneously with or independently of step h), a step l) of causing the refrigerant fluid to flow along the heat exchanger (100) is performed.

20. The method according to one or more of claims 13 to 19, characterized in that The method further comprises a step m) of controlling the opening of the opening / closing valve (55) so that the refrigerant fluid passes along the auxiliary pipeline, and a step n) of connecting the closed loop (C) fluid to the insulating space (20) by means of the auxiliary pipeline (50), wherein the auxiliary pipeline (50) is provided with an inlet section (51) for the refrigerant fluid and an outlet section (52) for the refrigerant fluid, wherein the inlet section (51) is arranged along a first length (T) of the closed loop between the evaporation device and the at least one compressor, and the outlet section (52) is connected to the insulating space (20) so that carbon dioxide in gaseous form flows into the insulating space (20).

21. The method according to claim 20, characterized in that The step m) is preceded by a step o) of detecting a fire in the insulating space (20).

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